An electrically-powered visual display unit (VDU), commonly known as a screen or a monitor, designed for displaying graphical information under program control in colour, e.g., measured values or images from other devices. Colour is necessary when separating the information of multiple parameters making it easier for the user to read the values. A keyboard may be connected to the unit for interactive manipulation of the data by an operator. This group of devices is the product identifier for the monitor only, which will not include the device(s) from which the data is generated and includes different screen technologies, e.g., cathode-ray tube (CRT) or liquid crystal display (LCD).